This invention is generally directed to developer compositions, and more specifically, the present invention relates to developer compositions with coated carrier components, or coated carrier particles and processes thereof. More specifically, the present invention relates to compositions, especially carrier compositions comprised of a core and thereover a polymer or mixture of polymers, and wherein the carriers are prepared by the utilization of high shear mixers to enable, for example, smooth coatings on the carrier and complete, or substantially complete coating of the carrier core, thereby resolving or minimizing problems encountered with the prior art processes wherein kilns are, for example, used and which kilns are free of impellers and thus high shear forces are not believed to be selected.
In embodiments of the present invention, the carrier particles are comprised of a core with a first polymer coating thereover of, for example, a fluoropolymer, a styrene polymer, a styrene acrylate, a styrene methacrylate, polymethylmethacrylate, the polymers of the above recited copending applications, such as terpolymers, such as terpolymers of styrene, butadiene and dimethylaminoethyl methacrylate, terpolymers of styrene, butadiene and alkyl aminoethyl methacrylates or acrylates with alkyl amine groups higher in carbon chain length than methyl, such as t-butylaminoethyl methacrylate, diethylaminoethyl methacrylate, diisopropylaminoethyl methacrylate, and the like. The carrier may include the first polymer coating thereover in admixture with other suitable polymers, and more specifically, with a suitable known second polymer, such as a fluoropolymer, polymethylmethacrylate, poly(urethane), especially a crosslinked polyurethane, such as a poly(urethane)polyester and the like, and moreover, the polymer coating may contain a conductive component, such as carbon black, and which conductive component is preferably dispersed in the polymer coating. With the conductive component, there may be enabled carriers with increased developer triboelectric response at relative humidities of from about 20 to about 90 percent, improved image quality performance, excellent high conductivity ranges of from about 10.sup.-10 to about 10.sup.-7 (ohm-cm).sup.-1, a triboelectrical charge, for example a carrier triboelectric charge range of from about a plus (positive charge) 20 to about 150 microcoulombs per gram, and preferably from about a positive 20 to about a positive 90 microcoulombs per gram, wherein the carrier charge is stable over extended time periods. Stable refers, for example, to minimal or substantially no changes in the carrier characteristics, for example, the triboelectric charge will not usually vary by more than 10 percent after being utilized for extended cycle times, such as from about 10,000 developed prints to about 50,000 developed prints in a xerographic or digital imaging apparatus.
The carrier particles of the present invention can be selected for a number of different xerographic copiers and printers, such as high speed color xerographic copiers, printers, digital copiers, and more specifically, wherein colored copies with excellent image resolution and substantially no background deposits are achievable in copiers, printers, digital copiers, and the combination of xerographic copiers and digital systems. Developer compositions comprised of the carrier particles illustrated herein and prepared, for example, by a dry or solution coating process are generally useful in electrostatographic or electrophotographic imaging systems, especially xerographic imaging and printing processes, and digital processes. Additionally, the invention developer compositions comprised of substantially conductive carrier particles are useful in imaging methods wherein relatively constant conductivity parameters are desired. Furthermore, in the aforementioned imaging processes the triboelectric charge on the carrier particles can be preselected depending on the polymer composition and dispersant component applied to the carrier core, the type and amount of the optional conductive component selected and the high shear mixing apparatus used.